Fig. 2. Unidirectional secretory, unidirectional reabsorptive, and net urate fluxes by chick PTCs following treatment with estrone sulfate (10 µmol l^–1, 500 µmol l^–1, or 2500 µmol l^–1). Estrone sulfate was administered to the interstitial side of the epithelium only (at t=0). Data are presented as the percentage of the paired control secretory flux and are means ± S.E.M. of four (10 µmol l^–1 and 500 µmol l^–1) and 10 (2500 µmol l^–1) preparations. ^*Significantly different from paired control flux (P<0.05, paired t-test).